Bacterial overgrowth is a condition in which the normal gastrointestinal bacterial flora is overtaken by proliferation of undesirable bacteria. It frequently occurs in patients in a weakened state of health, such as patients with compromised immunity, including transplant patients, AIDS patients, scleroderma patients, etc. The condition is usually marked by bloating, diarrhea and/or constipation, liquid stools, uncontrollable belching, and/or esophagal refluxing. S. A. Kaye et al., British Journal of Rheumatology, Vol. 34, p. 265 (1995) describes the condition of small bowel bacterial overgrowth in systemic sclerosis.
In some cases the overgrowth is due to a specific bacterium, such as a C. difficile, in other cases it may be due to a mixture of bacterial species and other organisms such as yeast, parasitic pathogens or viral pathogens.
Known treatments for gastrointestinal bacterial overgrowth include a variety of antibiotics, sulfa drugs and anti-yeast medications. Unfortunately, these medications, while often effective, are only useful for limited time periods since prolonged administration can cause serious complications such as selective propagation of antibiotic-resistant populations often more noxious, such as C. difficile. Antibiotics, sulfa drugs and anti-yeast medications do not eliminate the underlying cause of the bacterial overgrowth, and thus, gastrointestinal bacterial overgrowth is likely to recur in an aggravated form upon cessation of treatment. Furthermore, other undesirable consequences occur when the administration of antibiotics, sulfa drugs and anti-yeast medications is terminated, such as, for example, new overgrowth with different pathogens.
It is well known that immunoglobulins are the first line of defense against pathogens, and it is generally recognized that the main activity of immunoglobulins is in the circulating blood. A notable exception is the colostrum, the first postpartum milk, rich in immunoglobulins of the IgG and IgA type. These immunoglobulins protect newborn mammals which have immature immune systems against infections. This passive immunization via colostrum has been recognized for a long time as being particularly important for neonate survival.
Use of colostrum or its derivatives for the treatment of some gastroenteric diseases has been reported. See, for example, C. O. Tacket et al., Enterotoxigenic Escherichia coli (frequent cause of traveller's diarrhea), The New England Journal of Medicine, Vol. 318, p. 1240, 1988; P. Heaton, Case Report: Persistent Diarrhea, Archives of Diseases in Childhood, Vol. 65, p. 813, 1990; and Traveller diarrhea, Lancet, Editorial, p. 144, 1988.
Immunoglobulins, mainly immunoglobulin G, abbreviated "IgG", can be isolated from human plasma by a variety of techniques, well known in the art. Use of isolated immunoglobulins for intramuscular use or more highly purified immunoglobulins for intravenous usage is known in the medical arts. U.S. Pat. No. 4,477,432 discloses the oral administration of human immunoglobulins to prevent or treat enteric infections in humans.
Prior to the present invention described herein, it was generally assumed that only human immunoglobulins, i.e., immunoglobulins derived from human blood, plasma or serum, could be used for the treatment of human diseases. Furthermore, it is known that an intramuscular or intravenous use of immunoglobulins derived from animals such as goats, cows and horses is likely to cause a variety of undesirable side effects, such as serious allergic reactions, serum sickness, or anaphylactic shock.